Dynamic Touch Threshold Adjustment for Multi-Finger Detection
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Solution Overview
Problem
Conventional capacitive touch panels face challenges in accurately detecting touch coordinates, particularly with multi-finger inputs and large-area touches, due to limited sensing line resolution and susceptibility to noise, leading to misjudgment of touch points and coordinate shifts.
Innovation Solution
A touch sensing method that dynamically adjusts the touch threshold value based on sensing difference values, using two-dimensional high-pass filtering to enhance differences between sensing points, and expands touch regions to calculate gravity center positions, improving detection accuracy and resolving issues with multi-finger inputs and large-area presses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed threshold value is used for touch detection, then the detection process is simple, but multi-finger touches and large-area presses cannot be accurately distinguished leading to coordinate misjudgment
Solution Approach 1:
The patent implements dynamic threshold adjustment by calculating a local threshold for each sensing point based on the sensing values of adjacent sensing points. This local threshold adapts to the specific characteristics of each region, enabling accurate distinction between multi-finger touches and large-area presses while maintaining detection simplicity through automated calculation.
Solution Approach 2:
The patent changes the threshold parameter from a fixed global value to a dynamic local value that varies across different sensing points. By calculating thresholds based on local sensing value variations, the system adapts to different touch scenarios (single-finger, multi-finger, large-area press) and resolves coordinate misjudgment issues.
2Measurement precision
If linear interpolation is used to improve coordinate accuracy, then single-point touch precision improves, but the number of resolvable fingers remains limited by sensing line density
Solution Approach 1:
The patent segments the touch detection process into multiple independent sensing points arranged in a matrix, with each point having its own local threshold calculation. This segmentation allows independent analysis of capacitance changes at each point, enabling accurate detection of multiple simultaneous touch points without being limited by the overall sensing line density.
Solution Approach 2:
The patent transitions from one-dimensional sensing line detection to two-dimensional sensing point detection. By arranging sensing points in a matrix and performing local threshold calculations across both dimensions, the system can resolve multiple fingers touching at different positions simultaneously, overcoming the limitations of linear interpolation in one dimension.
3Reliability
If the sensing line area is increased to improve signal strength, then detection sensitivity improves, but the number of sensing lines that can be arranged decreases reducing resolution
Solution Approach 1:
The patent applies local quality by calculating unique local thresholds for each sensing point based on its specific surroundings. This allows each sensing point to optimally detect touches in its local region, maintaining high sensitivity without requiring increased sensing line area, thereby preserving the ability to arrange dense sensing lines for high resolution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively enhances the accuracy of touch detection, preventing misjudgment of touch points and coordinate shifts, ensuring precise determination of touch coordinates regardless of signal strength or noise interference.
Implementation Method 1
when the human body approaches to a capacitive touch panel, a capacitance generated between a transparent electrode of the capacitive touch panel and the human body due to electrostatic binding is varied. By measuring capacitance variations of sensing lines on the capacitive touch panel, a position of a touch point is determined.
Implementation Method 2
a capacitance generated between a transparent electrode of the capacitive touch panel and the human body due to electrostatic binding is varied
Data Source
AI summary
A touch sensing method for a touch panel is provided. The touch sensing method includes following steps. First, a plurality of sensing values of a plurality of sensing points are received so as to calculate a plurality of sensing difference values according to the sensing values. Next, a touch threshold value is determined according to at least one (e.g., a maximum one) of the sensing difference values. Then, the sensing difference values are compared with the touch threshold value to determine the coordinates of the touched ones of the sensing points according to the comparison result.